The invention relates to an apparatus for attaching a vehicle axle to an axle suspension of a vehicle, in particular of a utility vehicle.
U.S. Pat. No. 5,328,159 discloses an attachment means, in which the vehicle axle which is equipped with vehicle wheels is mounted on a vehicle frame by means of an axle suspension. This axle bearing or axle suspension comprising axle springs which are supported on the vehicle frame at the one end and on the vehicle axles at the other. Such an axle spring is usually supported indirectly on the vehicle axle by means of a spring caliper which is mounted on the vehicle axle. In order to secure the axle spring to the vehicle axle, the axle spring has spring clips, so-called xe2x80x9cspring clampsxe2x80x9d which engage over the sides of the vehicle axle and are attached to a counterplate which is mounted on the vehicle axle opposite the spring caliper. Using the spring clips, a pre-stress is formed between the counterplate and spring caliper, said pre-stress being normally greater than the axle loads which are usually to be expected and borne by the axle spring.
This means of attachment for attaching the axle spring to the vehicle axle is used to transmit to the vehicle frame in a sprung fashion the forces and moments acting on the vehicle wheels or on the vehicle axle. For example, when the vehicle is braking and accelerating, tilting moments occur in the vehicle axle. Lateral forces on the vehicle wheels, for example during cornering or when travelling over an obstacle with an acute angle between the respective vehicle wheel and the obstacle, lead to lateral guiding forces in the vehicle axle. In addition, supporting forces occur which result from the overall mass of the vehicle and which are briefly multiplied when the vehicle travels through a pothole, for example.
In order to be able to secure the above mentioned spring caliper and the aforementioned counterplate as quickly and economically as possible during production line assembly, the spring caliper and the counterplate are each welded to the spring axle. Because large forces and moments have to be transmitted via the spring caliper and the counterplate, correspondingly long and thick weld seams have been formed until now. In this context, in particular in the tensile zone and compressive zone of the axle, so-called xe2x80x9cthermal notchesxe2x80x9d occur which reduce the strength of the vehicle axle in the vicinity of the weld seam owing to thermal stresses which arise in the structure of the material during the welding process. The vehicle axle can fail in the vicinity of the thermal notches at an earlier point than can be expected on the basis of the dimensions of the vehicle axle. In order to compensate for this, the vehicle axles must be correspondingly over-dimensioned.
Because the spring caliper and the counterplate are each supported on the upper side and underside of the vehicle axle, the stability, and thus the thickness of the material of the vehicle axle must be additionally increased if high spring clip pre-stresses are to be implemented.
The present invention is aimed at overcoming one or more of the problems identified above.
The present invention is concerned with the problem of configuring a means of attachment of the type mentioned at the beginning, to such an extent that the load-bearing capacity of the vehicle axle or its service life is increased.
Furthermore, there is a need to adapt the means of attachment more easily to different variants of axle suspensions and axle arrangements. Finally, the intention is that the means of attachment will be more economical to construct.
As a solution, the invention proposes a means of attachment with the features of claim 1.
The invention is based on the general idea of using two angular parts to reinforce the vehicle axle in the region in which the axle spring engages on the vehicle axle, the angular part completely engaging around the vehicle axle and being supported one against the other in such a way that the vehicle axle is at least largely relieved of loading by the pre-stress of the spring clips. The spring caliper and the counterplate are then formed on these angular parts so that long weld seams with a correspondingly deep penetration can be dispensed with, thus minimizing the formation of thermal notches in the vehicle axle. Correspondingly, either the vehicle axle loading can be increased or, with unchanged axle loading, the service life of the vehicle axle can be increased or the material thickness of the vehicle axle reduced. Moreover, the formation of the long weld seams is dispensed with, simplifying the fabrication of the attachment means.
Such angular parts can be embodied as punched parts which are deformed by bending and which can be fabricated particularly economically.
Since the angular parts bear against the vehicle axle and completely enclose it, a positive lock is formed between the angular parts and the vehicle axle, which lock makes it possible to transmit tilting moments from the vehicle axle to the axle suspension. Supporting forces are transmitted by means of the angular parts which bear against the upper side and the underside of the vehicle axle.
The angular parts are secured to the vehicle axle in order to transmit lateral guiding forces. A portion of this securement is formed by the frictional locking with which the angular parts engage around the vehicle axle. Another portion of this securement is effected by, for example, welding the angular parts to the vehicle axle in the vicinity of the neutral fibre of the vehicle axle for vertical bending stresses. In this way, a highly effective securement for transmitting lateral guiding forces is made possible without perceptibly reducing the rigidity or the strength of the vehicle axle.
The term neutral fibre is usually used to refer to the region of a component which experiences the smallest expansions when the component is subjected to bending stresses. In the present case, this neutral fibre corresponds to an essentially horizontally extending longitudinal centre plane of the vehicle axle in which vertically extending bending stresses of the vehicle axle do not bring about any expansion.
According to the invention, the angular parts are each formed from a vertical section and from a horizontal section which are connected to one another in a corner region of the angular part. Here, the vertical sections of the angular parts are secured laterally to the vehicle axle and welded to the horizontal section of the respective other angular part in such a way that high tensile forces and compressive forces can be transmitted between the angular parts. The horizontal sections of the angular parts form, or are fitted with, the spring caliper or the counterplate here.
In accordance with one advantageous embodiment of the attachment means according to the invention, firstly an underside of the spring caliper, with which the spring caliper bears against the upper horizontal section of the one angular part can have an inclination with respect to an upper side of the spring caliper, which side faces away from it and on which the axle spring is supported. Secondly, an upper side of the counterplate with which the counterplate bears against the lower horizontal section of the other angular part can then have the same inclination with respect to an underside, facing away therefrom, of the counterplate to which the spring clips are attached. These measures make it possible to vary in any desired way the installation position of the vehicle axle, i.e. the angular orientation of the axle cross section with a low degree of expenditure, in order to adapt the vehicle axle to the respective axle suspension. The inclination between the underside and upper side of the spring caliper and of the corresponding inclination between the upper side and underside of the counterplate enables the angular parts which are attached to the vehicle axle to be arranged in a cross section, laterally with respect to the longitudinal direction of the vehicle axle, rotated through the angle of the aforesaid inclination in each case. This adaptation of the installation position of the vehicle axle is effected here by means of the easily executed adaptation of the spring caliper which is easy to fabricate, and of the counterplate which is also easy to fabricate. Changes to the angular parts, to the vehicle axle or to the vehicle axle during the mounting of the angular parts are not necessary to achieve this.
According to one particularly advantageous embodiment the attachment means according to the invention, each vertical section of the angular parts may be formed from a base which is arranged on the associated horizontal section, and from two limbs which start from this base and extend bearing essentially vertically and laterally against the vehicle axle. This measure results, in particular, in an additional saving in material.
In order to adapt the vertical sections to different loading situations, which may result, for example, from the installation position of the vehicle axle, from the type of the vehicle and from the spring track, the distance between the limbs may either be constant along their vertical extent, or decrease up to the centre of the limb and then increase again or increase up to the centre of the limb and then decrease again.
Furthermore, there may be provision for each vertical section to have an inner side which faces the vehicle axle and whose contour is formed so as to be essentially complementary to the external contour of the associated region of the vehicle axle. This measure makes it possible to adapt the attachment means according to the invention to different axle body shapes and to form a positive lock between the vehicle axle and the angular parts welded to one another, in order to transmit tilting moments.
Further important features and advantages of the attachment means according to the invention emerge from the sub-claims, from the drawings and from the associated description of the figures.
The aforementioned features and the features yet to be mentioned below, can, of course, be used not only in the respectively specified combination but also in other combinations or in isolation, without departing from the framework of the present invention.